Measuring trucks real emissions to improve fleet performance

Alsa, a Spanish private bus transport company, decided to hire Opus RSE to analyze the buses fleet condition.


200 buses of the company were analyzed by the RSD equipment of Opus RSE, to measure their real-driving emissions and identify possible high-emitting buses.

The project was done in collaboration with Repsol, the most important spanish energy and petrochemical company. It was very important Repsol was also introduced in the project, as high-emitting vehicles are associated to non-efficiency, consuming much more fuel than needed.


 The measurements were done in different bus stations of Alsa. The buses could drive normally when their emissions were measured.

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  • The RSD is placed in the stations where the buses are.
  • All the buses that access the station are measured by the RSD.
  • The buses fleet emissions are analyzed in detail. Individual emissions of each bus are evaluated considering the individual consumption and mileage of each bus.
  • Possible mismatched buses that are emitting high amounts of CO, NOx, HC or PM are identified for repair.
  • Emission reductions from new or repaired buses can be quantified (tones /year savings).


The measurements showed that the fleet had very high emissions of hydrocarbons and particulate matter. A large percentage of the buses did not meet the European Standard limits in these two pollutants, when driving in real conditions.


It was very alarming to find that 9 of the buses were emitting even 11 times over the average of the rest of the fleet.


By analyzing the emissions, Opus RSE could estimate enormous savings in fuel consumption for Alsa.


Finally, some mechanical failures of the buses could be proposed, just by analysing the emissions. This is additional reason to use RSD to frequently monitor and control the emissions of the fleet. Finding mechanical failures is cheap and does not affect daily operations.


Opus RSE

Gaztambide, 45

28015, Madrid (Spain)

Phone: (+34) 91 559 28 68


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